Redo Log File Options

To mine data in the redo log files, LogMiner needs information about which redo log files to mine. Changes made to the database that are found in these redo log files are delivered to you through the V$LOGMNR_CONTENTS view.

You can direct LogMiner to automatically and dynamically create a list of redo log files to analyze, or you can explicitly specify a list of redo log files for LogMiner to analyze, as follows:

• Automatically

  If LogMiner is being used on the source database, then you can direct LogMiner to find and create a list of redo log files for analysis automatically. Use the CONTINUOUS_MINE option when you start LogMiner with the DBMS_LOGMNR.START_LOGMNR procedure, and specify a time or SCN range. Although this example specifies the dictionary from the online catalog, any LogMiner dictionary can be used.

  Note:

  The CONTINUOUS_MINE option requires that the database be mounted and that archiving be enabled.

  LogMiner will use the database control file to find and add redo log files that satisfy your specified time or SCN range to the LogMiner redo log file list. For example:

  ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MON-YYYY HH24:MI:SS';
  EXECUTE DBMS_LOGMNR.START_LOGMNR( -
     STARTTIME => '01-Jan-2012 08:30:00', -
     ENDTIME => '01-Jan-2012 08:45:00', -
     OPTIONS => DBMS_LOGMNR.DICT_FROM_ONLINE_CATALOG + -
     DBMS_LOGMNR.CONTINUOUS_MINE);
  

  (To avoid the need to specify the date format in the PL/SQL call to the DBMS_LOGMNR.START_LOGMNR procedure, this example uses the SQL ALTER SESSION SET NLS_DATE_FORMAT statement first.)

  You can also direct LogMiner to automatically build a list of redo log files to analyze by specifying just one redo log file using DBMS_LOGMNR.ADD_LOGFILE, and then specifying the CONTINUOUS_MINE option when you start LogMiner. The previously described method is more typical, however.

• Manually

  Use the DBMS_LOGMNR.ADD_LOGFILE procedure to manually create a list of redo log files before you start LogMiner. After the first redo log file has been added to the list, each subsequently added redo log file must be from the same database and associated with the same database RESETLOGS SCN. When using this method, LogMiner need not be connected to the source database.

  For example, to start a new list of redo log files, specify the NEW option of the DBMS_LOGMNR.ADD_LOGFILE PL/SQL procedure to signal that this is the beginning of a new list. For example, enter the following to specify /oracle/logs/log1.f:

  EXECUTE DBMS_LOGMNR.ADD_LOGFILE( -
     LOGFILENAME => '/oracle/logs/log1.f', -
     OPTIONS => DBMS_LOGMNR.NEW);
  

  If desired, add more redo log files by specifying the ADDFILE option of the PL/SQL DBMS_LOGMNR.ADD_LOGFILE procedure. For example, enter the following to add /oracle/logs/log2.f:

  EXECUTE DBMS_LOGMNR.ADD_LOGFILE( -
     LOGFILENAME => '/oracle/logs/log2.f', -
     OPTIONS => DBMS_LOGMNR.ADDFILE);
  

  To determine which redo log files are being analyzed in the current LogMiner session, you can query the V$LOGMNR_LOGS view, which contains one row for each redo log file.